Tentatively called the Tengah Line and Seletar Line, these two could potentially meet at the Greater Southern Waterfront and combine into a single line.
French firm Alstom will be supplying 17 new trains equipped with condition monitoring systems to increase the capacity of the North-East Line and Circle Line.
Commuters travelling between Tuas and Pasir Ris on the East-West Line will not have a smooth journey for a while, due to the fallout from last week's collision.
Tuas commuters had to account for additional travelling time this morning, due to a closure of the MRT line between Joo Koon and Gul Circle staions.
The Tuas West Extension runs on the new communications-based signalling system and not the fixed-block one that the rest of the East-West Line is operating on.
The entire project is expected to cost $3.7 billion, with the Government stating in its latest Budget book that the advanced works would cost $30.6 million.
Aecom Singapore has a strong track record and has helped to design the Circle Line, Downtown Line, Thomson-East Coast Line and the Tuas West Extension.
Transport Minister Lui Tuck Yew announced that engineering studies are being done to explore the extension of the Jurong Region Line to join the Circle Line.